Surfacing welding method for nickel-based alloy

Abstract

The invention provides a surfacing welding method for nickel-based alloy, and relates to the technical field of surfacing welding. The surfacing welding method of the nickel-based alloy comprises the following steps that an alloy steel part is preheated to 150 DEG C or above, nickel-based alloy surfacing is conducted on the surface of the alloy steel part, and the alloy steel part is fed into a heat treatment furnace to be subjected to stress relief heat treatment; and repeating the steps for one or more times. Nickel-based alloy surfacing is carried out for multiple times, stress relief heat treatment is carried out after surfacing each time, welding residual stress superposed in the nickel-based alloy surfacing process is dispersed for multiple times and released, welding residual stress generated in the surfacing welding process is reduced for multiple times in the surfacing welding process, and a welding seam structure is uniform; and the situation that the middle or edge position of a surfacing layer is cracked due to overlarge residual stress in the surfacing process of the nickel-based alloy is avoided, the quality of the surfacing layer of the nickel-based alloy is guaranteed, and then the in-service life of a welded product is prolonged, and the use safety of the welded product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of cladding welding, and in particular to a cladding welding method for a nickel-based alloy. Background Art

[0002] At present, in the manufacturing process of reactor pressure vessel products, the key components of the pressure vessel, such as the top cover components, pipe components, and pipe section components, all need to be welded with a nickel-based alloy cladding layer on the alloy steel surface as an anti-corrosion isolation layer to prevent environmental corrosion of the alloy steel components. The size of the key components of the pressure vessel is large, with the diameter of some workpieces Φ≥4000mm and the height of some key components H≥5000mm. Therefore, the area of ​​the nickel-based alloy cladding layer is large, and the maximum cladding thickness can reach 35mm, resulting in large welding residual stress. In the cladding process of nickel-based alloy welding materials, since nickel-based alloys are sensitive to crystallization cracks and high-temperature low-plasticity cracks, under the action of welding residual stress, it is easy to crack at the interface between the cladding layer and the alloy steel parent material or at the edge of the cladding layer during the cladding process, which in turn causes the nickel-based alloy to peel off at the interface between the alloy steel parent material. Summary of the invention

[0003] The problem solved by the invention is how to solve the problem that cracks are likely to occur at the joint surface between the cladding layer and the parent material or at the edge of the cladding layer during the cladding process of the nickel-based alloy.

[0004] In order to solve the above problems, the present invention provides a cladding welding method for a nickel-based alloy.

[0005] In a first aspect, the present invention provides a nickel-based alloy cladding welding method, comprising the following steps:

[0006] Alloy steel parts are preheated to above 150°C, nickel-based alloy is clad on the surface of the alloy steel parts, and then sent to the heat treatment furnace for stress relief heat treatment;

[0007] Repeat the above steps one or more times.

[0008] Optionally, the method specifically includes the following steps:

[0009] The alloy steel parts are preheated to above 150°C, the surface of the alloy steel parts is subjected to the first stage of nickel-based alloy surfacing, and then sent into the heat treatment furnace for the first stage of stress relief heat treatment;

[0010] The alloy steel parts are preheated to above 150°C, the second stage of nickel-based alloy surfacing is performed on the surface of the alloy steel parts, and then sent to the heat treatment furnace for the second stage of stress relief heat treatment;

[0011] The alloy steel parts are preheated to above 150°C, the surface of the alloy steel parts is subjected to the third stage of nickel-based alloy surfacing, and then sent to the heat treatment furnace for the third stage of stress relief heat treatment;

[0012] The alloy steel parts are preheated to above 150°C, the surfaces of the alloy steel parts are subjected to fourth-stage nickel-based alloy surfacing, and then sent to a heat treatment furnace for fourth-stage stress relief heat treatment.

[0013] Optionally, the treatment time of the four stages of stress relief heat treatment increases step by step, and the total treatment time of the four stages of stress relief heat treatment does not exceed 20 hours.

[0014] Optionally, the stress relief heat treatment includes a first temperature rising section, a second constant temperature section, a third temperature rising section, a fourth stress relief section and a fifth temperature falling section.

[0015] Optionally, the heating rates of the first heating stage and the third heating stage are not higher than 55°C / hour, and the cooling rate of the fifth cooling stage is not higher than 55°C / hour.

[0016] Optionally, the temperature of the second constant temperature section is 200-300° C., and the time of the second constant temperature section is 0.5-1.5 hours.

[0017] Optionally, the temperature of the fourth stress relief section is 615±15°C, the treatment time of the fourth stress relief section of the first stage stress relief heat treatment is 1-1.5 hours, the treatment time of the fourth stress relief section of the second stage stress relief heat treatment is 1.5-2 hours, the treatment time of the fourth stress relief section of the third stage stress relief heat treatment is 2-3 hours, and the treatment time of the fourth stress relief section of the fourth stage stress relief heat treatment is 4-5 hours.

[0018] Optionally, the nickel-based alloy surfacing thickness in the first stage is 4-4.5 mm, the nickel-based alloy surfacing thickness in the second stage is 10-12 mm, the nickel-based alloy surfacing thickness in the third stage is 10-12 mm, and the nickel-based alloy surfacing thickness in the fourth stage is 6-12 mm.

[0019] Optionally, before the step of preheating the alloy steel component to above 150° C., the step further includes: cleaning the surface of the alloy steel component to be welded to remove the oxide film.

[0020] Optionally, the alloy steel component is a low alloy steel with a total amount of alloy elements less than 5%.

[0021] The beneficial effect of the nickel-based alloy surfacing welding method of the present invention is: the nickel-based alloy surfacing is performed multiple times, and stress relief heat treatment is performed after each surfacing, so that the welding residual stress superimposed in the nickel-based alloy surfacing process is dispersed and released multiple times, and the welding residual stress generated in the surfacing welding process is reduced multiple times during the surfacing welding process, so that the weld structure is uniform, and cracks in the middle or edge of the surfacing layer caused by excessive residual stress during the nickel-based alloy surfacing process are avoided, thereby ensuring the quality of the nickel-based alloy surfacing layer, thereby increasing the service life and safety of the welding product. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A temperature variation curve diagram of the first stage stress relief heat treatment of an embodiment of the present invention;

[0023] Figure 2 A temperature variation curve diagram of the second stage stress relief heat treatment of an embodiment of the present invention;

[0024] Figure 3 A temperature variation curve diagram of the third stage stress relief heat treatment of an embodiment of the present invention;

[0025] Figure 4 FIG. 4 is a temperature variation curve diagram of the fourth stage stress relief heat treatment in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0028] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0029] In view of the problems existing in the above-mentioned related technologies, this embodiment provides a cladding welding method for a nickel-based alloy.

[0030] A nickel-based alloy cladding welding method provided in an embodiment of the present invention comprises the following steps:

[0031] Alloy steel parts are preheated to above 150°C, nickel-based alloy is clad on the surface of the alloy steel parts, and then sent to the heat treatment furnace for stress relief heat treatment;

[0032] Repeat the above steps one or more times.

[0033] In the present embodiment, nickel-based alloy surfacing is performed multiple times, and stress relief heat treatment is performed after each surfacing, so that the welding residual stress superimposed during the nickel-based alloy surfacing is dispersed and released multiple times, and the welding residual stress generated during the surfacing welding process is reduced multiple times during the surfacing welding process to make the weld structure uniform, avoid cracking in the middle or edge of the surfacing layer due to excessive residual stress during the nickel-based alloy surfacing process, ensure the quality of the nickel-based alloy surfacing layer, and thereby increase the service life and safety of the welding product.

[0034] Specifically, when the total thickness of the nickel-based alloy cladding layer reaches 35 mm, the quality of the nickel-based alloy cladding layer is inspected by non-destructive testing, and all welds are 100% qualified.

[0035] Optionally, the method specifically comprises the following steps:

[0036] The alloy steel parts are preheated to above 150°C, the surface of the alloy steel parts is subjected to the first stage of nickel-based alloy surfacing, and then sent into the heat treatment furnace for the first stage of stress relief heat treatment;

[0037] The alloy steel parts are preheated to above 150°C, the second stage of nickel-based alloy surfacing is performed on the surface of the alloy steel parts, and then sent to the heat treatment furnace for the second stage of stress relief heat treatment;

[0038] The alloy steel parts are preheated to above 150°C, the surface of the alloy steel parts is subjected to the third stage of nickel-based alloy surfacing, and then sent to the heat treatment furnace for the third stage of stress relief heat treatment;

[0039] The alloy steel parts are preheated to above 150°C, the surfaces of the alloy steel parts are subjected to fourth-stage nickel-based alloy surfacing, and then sent to a heat treatment furnace for fourth-stage stress relief heat treatment.

[0040] In this optional embodiment, nickel-based alloy surfacing is carried out in four stages, and stress relief heat treatment is performed after each stage of surfacing, so that the welding residual stress superimposed during the nickel-based alloy surfacing process is released in stages. The surfacing welding process is divided into four stages to reduce the welding residual stress generated during the surfacing welding process, make the weld structure uniform, avoid cracking in the middle or edge of the surfacing layer due to excessive residual stress during the nickel-based alloy surfacing process, and ensure the quality of the nickel-based alloy surfacing layer.

[0041] Specifically, after each stage of stress relief heat treatment is completed, the alloy steel parts are removed from the heat treatment furnace and are cooled to below 150°C.

[0042] Optionally, the treatment time of the four stages of stress relief heat treatment increases step by step, and the total treatment time of the four stages of stress relief heat treatment does not exceed 20 hours.

[0043] In this optional embodiment, as the thickness of the cladding layer increases, the welding residual stress gradually increases, so the longer the stress relief heat treatment time is, the better the effect of eliminating the welding residual stress is. However, the stress relief heat treatment time of the cladding layer cannot be too long, and the total stress relief heat treatment time of the overall workpiece manufacturing cannot exceed the requirement of 20 hours.

[0044] Optionally, the stress relief heat treatment includes a first temperature rising section, a second constant temperature section, a third temperature rising section, a fourth stress relief section and a fifth temperature falling section.

[0045] In this optional embodiment, after the first heating to the second constant temperature section, the workpiece is preheated to make the workpiece temperature uniform, and then the temperature is raised to the fourth stress relief section to perform stress relief heat treatment to make the weld structure uniform.

[0046] Optionally, the heating rates of the first heating stage and the third heating stage are not higher than 55°C / hour, and the cooling rate of the fifth cooling stage is not higher than 55°C / hour.

[0047] In this optional embodiment, if the heating rate is too fast, the temperature of the workpiece will be uneven, the surface temperature will be high, and the center temperature will be low, which will accelerate the diffusion of bubbles and cracks in the material and reduce the mechanical properties; if the heating rate is too slow, the grains of the material will grow too large, and the hardness of the material will decrease; slow heating can ensure that the overall temperature of the workpiece is uniform. If the material's cooling rate is too fast, it will affect the material's microstructure and performance, reducing the material's plasticity and toughness; if the cooling rate is too slow, it will increase the time cost; slow cooling can make the metal structure reach equilibrium.

[0048] Specifically, in the fifth cooling stage, the workpiece is cooled to below 300° C. and can be taken out of the furnace.

[0049] Optionally, the temperature of the second constant temperature section is 200-300° C., and the time of the second constant temperature section is 0.5-1.5 hours.

[0050] In this optional embodiment, the temperature is first raised to 200-300°C and then raised to the stress relief treatment temperature, which can ensure that the overall temperature of the workpiece is uniform.

[0051] Optionally, the temperature of the fourth stress relief section is 615±15°C, the treatment time of the fourth stress relief section of the first stage stress relief heat treatment is 1-1.5 hours, the treatment time of the fourth stress relief section of the second stage stress relief heat treatment is 1.5-2 hours, the treatment time of the fourth stress relief section of the third stage stress relief heat treatment is 2-3 hours, and the treatment time of the fourth stress relief section of the fourth stage stress relief heat treatment is 4-5 hours.

[0052] In this optional embodiment, as the thickness of the weld overlay increases, the welding residual stress gradually increases, so the longer the stress relief heat treatment time is, the better the effect of eliminating the welding residual stress is.

[0053] Optionally, the nickel-based alloy surfacing thickness in the first stage is 4-4.5 mm, the nickel-based alloy surfacing thickness in the second stage is 10-12 mm, the nickel-based alloy surfacing thickness in the third stage is 10-12 mm, and the nickel-based alloy surfacing thickness in the fourth stage is 6-12 mm.

[0054] Specifically, in the first stage of nickel-based alloy surfacing, the surface of the alloy steel parts is completely covered with a layer of nickel-based alloy; in the second stage of nickel-based alloy surfacing and the third stage of nickel-based alloy surfacing, the surface of the alloy steel parts is completely covered with three layers of nickel-based alloy; in the fourth stage of nickel-based alloy surfacing, the surfacing is terminated after the total thickness of the nickel-based alloy surfacing layer in the technical requirements is reached.

[0055] Optionally, before the step of preheating the alloy steel component to above 150° C., the method further comprises the step of cleaning the surface of the alloy steel component to be welded to remove the oxide film.

[0056] Specifically, an aluminum-based iron-free grinding wheel is used to clean the surface of the alloy steel component to remove the oxide film on the surface of the alloy steel component or the surface of the nickel-based alloy cladding layer after heat treatment.

[0057] Optionally, the alloy steel component is a low alloy steel with a total amount of alloy elements less than 5%.

[0058] Specifically, in the manufacturing process of reactor pressure vessel products, low alloy steel is used in key components of the pressure vessel, such as the top cover component, the connecting pipe component and the connecting pipe section component.

[0059] The present invention is further described below in conjunction with specific embodiments.

[0060] Example 1, a method for welding a nickel-based alloy on the surface of a low-alloy steel component.

[0061] 1. Use an aluminum-based iron-free grinding wheel to clean and remove the oxide film on the surface to be welded of the low-alloy steel parts; after preheating the low-alloy steel parts to above 150°C, carry out the first layer of nickel-based alloy surfacing welding, and carry out the first stage of nickel-based alloy surfacing on the surface of the low-alloy steel parts. The surface of the low-alloy steel parent material is completely covered with a layer of nickel-based alloy, and the surfacing thickness is 4mm. After completion, send it into the heat treatment furnace for the first stage of stress relief heat treatment to reduce the welding residual stress of the first layer of nickel-based alloy surfacing layer. First, in the first heating stage, the heating rate is set to 55°C / hour, and the temperature is raised to 200°C to enter the second constant temperature stage, and the constant temperature preheating is performed for 0.5 hours, and then enter the third heating stage, according to the heating rate of 50°C / hour, the temperature is raised to 600°C, and the fourth stress relief stage is entered. The treatment time is 1 hour, and finally enter the fifth cooling stage, and the temperature is lowered at a cooling rate of 55°C / hour. After it drops to 300°C, it is removed from the heat treatment furnace;

[0062] 2. Use an aluminum-based iron-free grinding wheel to clean and remove the oxide film on the surface of the low-alloy steel parts to be welded; after preheating the low-alloy steel parts to above 150°C, perform the second stage of nickel-based alloy surfacing on the surface of the low-alloy steel parts, weld 3 layers, and the surfacing thickness is about 10mm. Send them into the heat treatment furnace for the second stage of stress relief heat treatment to reduce the welding residual stress of the second stage nickel-based alloy surfacing layer. First, in the first heating stage, the heating rate is set to 55°C / hour, and the temperature is raised to 300°C to enter the second constant temperature stage. Preheat at constant temperature for 1 hour, then enter the third heating stage, and heat up to 615°C at a heating rate of 50°C / hour, enter the fourth stress relief stage, and the treatment time is 1.5 hours. Finally, enter the fifth cooling stage, cool down at a cooling rate of 55°C / hour, and remove from the heat treatment furnace after it drops to 300°C;

[0063] 3. Use an aluminum-based iron-free grinding wheel to clean and remove the oxide film on the surface of the low-alloy steel parts to be welded; preheat the low-alloy steel parts to above 150°C, perform the third-stage nickel-based alloy surfacing on the surface of the low-alloy steel parts, weld 3 layers, and the surfacing thickness is about 12mm. Send them into the heat treatment furnace for the third-stage stress relief heat treatment to reduce the welding residual stress of the third-stage nickel-based alloy surfacing layer. First, in the first heating stage, the heating rate is set to 55°C / hour, and the temperature is raised to 300°C to enter the second constant temperature stage, and the constant temperature preheating is performed for 1 hour. Then, the third heating stage is entered, and the temperature is raised to 630°C at a heating rate of 50°C / hour. Enter the fourth stress relief stage, and the treatment time is 2 hours. Finally, enter the fifth cooling stage, cool down at a cooling rate of 55°C / hour, and remove from the heat treatment furnace after it drops to 300°C.

[0064] 4. Use an aluminum-based iron-free grinding wheel to clean and remove the oxide film on the surface to be welded of the low-alloy steel parts; preheat the low-alloy steel parts to above 150°C, perform the fourth stage of nickel-based alloy surfacing on the surface of the low-alloy steel parts, and the total surfacing thickness is about 35mm. The surfacing process is completely completed, and the parts are sent to the heat treatment furnace for the fourth stage of stress relief heat treatment to reduce the welding residual stress of the fourth stage nickel-based alloy surfacing layer. First, in the first heating stage, the heating rate is set to 55°C / hour, and the temperature is raised to 300°C to enter the second constant temperature stage, and the constant temperature preheating is performed for 1 hour, and then the third heating stage is entered, and the temperature is raised to 615°C at a heating rate of 50°C / hour, and the fourth stress relief stage is entered for a treatment time of 4 hours. Finally, the fifth cooling stage is entered, and the temperature is lowered at a cooling rate of 55°C / hour. After the temperature drops to 300°C, the parts are removed from the heat treatment furnace.

[0065] The product prepared in Example 1 was subjected to a nondestructive testing process, and the nondestructive testing included liquid penetrant testing (PT) and ultrasonic testing (UT). The test results showed that the weld structure was uniform, and cracks did not occur at the interface between the nickel-based alloy cladding layer and the base material, and there was no cracking at the edge of the nickel-based alloy cladding layer.

[0066] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A nickel-based alloy cladding welding method, characterized in that: The following steps are involved: The alloy steel parts are preheated to above 150°C, the surfaces of the alloy steel parts are clad with nickel-based alloy, and then sent to a heat treatment furnace for stress relief heat treatment; Repeat the above steps one or more times.

2. The nickel-based alloy cladding welding method according to claim 1, characterized in that: The specific steps include: The alloy steel component is preheated to above 150° C., the surface of the alloy steel component is subjected to first-stage nickel-based alloy surfacing, and then sent into a heat treatment furnace for first-stage stress relief heat treatment; The alloy steel component is preheated to above 150° C., the surface of the alloy steel component is subjected to second-stage nickel-based alloy surfacing, and then sent into a heat treatment furnace for second-stage stress relief heat treatment; The alloy steel component is preheated to above 150° C., the surface of the alloy steel component is subjected to third-stage nickel-based alloy surfacing, and then sent into a heat treatment furnace for third-stage stress relief heat treatment; The alloy steel component is preheated to above 150° C., the surface of the alloy steel component is subjected to fourth-stage nickel-based alloy surfacing, and then sent into a heat treatment furnace for fourth-stage stress relief heat treatment.

3. The cladding welding method of nickel-based alloy according to claim 2, characterized in that: The treatment time of the four stages of the stress relief heat treatment increases step by step, and the total treatment time of the four stages of the stress relief heat treatment does not exceed 20 hours.

4. The cladding welding method of nickel-based alloy according to claim 2, characterized in that: The stress relief heat treatment comprises a first temperature rising section, a second constant temperature section, a third temperature rising section, a fourth stress relief section and a fifth temperature falling section.

5. The nickel-based alloy cladding welding method according to claim 4, characterized in that: The heating rates of the first heating section and the third heating section are not higher than 55° C. / hour, and the cooling rate of the fifth cooling section is not higher than 55° C. / hour.

6. The nickel-based alloy cladding welding method according to claim 4, characterized in that: The temperature of the second constant temperature section is 200-300° C., and the time of the second constant temperature section is 0.5-1.5 hours.

7. The cladding welding method of nickel-based alloy according to claim 4, characterized in that: The temperature of the fourth stress relief section is 615±15°C, the treatment time of the fourth stress relief section of the first stage stress relief heat treatment is 1-1.5 hours, the treatment time of the fourth stress relief section of the second stage stress relief heat treatment is 1.5-2 hours, the treatment time of the fourth stress relief section of the third stage stress relief heat treatment is 2-3 hours, and the treatment time of the fourth stress relief section of the fourth stage stress relief heat treatment is 4-5 hours.

8. The nickel-based alloy cladding welding method according to claim 1, characterized in that: The nickel-based alloy surfacing thickness of the first stage is 4-4.5 mm, the nickel-based alloy surfacing thickness of the second stage is 10-12 mm, the nickel-based alloy surfacing thickness of the third stage is 10-12 mm, and the nickel-based alloy surfacing thickness of the fourth stage is 6-12 mm.

9. The nickel-based alloy cladding welding method according to claim 1, characterized in that: Before the step of preheating the alloy steel component to above 150° C., the method further comprises the step of cleaning the surface of the alloy steel component to be welded to remove the oxide film.

10. The nickel-based alloy cladding welding method according to claim 1, characterized in that: The alloy steel component is low alloy steel with a total amount of alloy elements less than 5%.

Images